Do Toenail Manganese and Iron Levels Reflect Brain Metal Levels or Brain Metabolism in Welders?

Details

• Personal Author:
  Dydak U ; Francis G ; Lee CG ; Monsivais H ; Nossa G ; Park JH ; Wells EM
• Description:
  Inhalation of welding fumes can cause metal accumulation in the brain, leading to Parkinsonian-like symptoms. Metal accumulation and altered neurochemical profiles have been observed using magnetic resonance imaging (MRI) in highly exposed welders, being associated with decreased motor function and cognition. While MRI is impractical to use as a health risk assessment tool in occupational settings, toenail metal levels are easier to assess and have been demonstrated to reflect an exposure window of 7-12 months in the past. Yet, it is unclear whether toenail metal levels are associated with brain metal levels or changes in metabolism, which are the root of potential health concerns. This study investigates whether toenail manganese (Mn) and iron (Fe) levels, assessed at several time points, correlate with brain Mn and Fe levels, measured by MRI, as well as brain GABA, glutamate (Glu), and glutathione (GSH) levels, measured by Magnetic Resonance Spectroscopy (MRS), in seventeen Mn-exposed welders. Quantitative T1 and R2* MRI maps of the whole brain, along with GABA, Glu, and GSH MRS measurements from the thalamus and cerebellum were acquired at baseline (T0). Toenail clippings were collected at T0 and every three months after the MRI for a year to account for different exposure periods being reflected by toenail clippings and MRI. Spearman correlations of toenail metal levels were run against brain metal and metabolite levels, but no significant associations were found for Mn at any timepoint. Cerebellar GSH positively correlated with toenail Fe clipped twelve months after the MRI (p = 0.05), suggesting an association with Fe exposure at the time of the MRI. Neither thalamic GABA nor Glu correlated with toenail Fe levels. In conclusion, this study cannot support toenail Mn as a proxy for brain Mn levels or metabolic changes, while toenail Fe appears linked to brain metabolic alterations, underscoring the importance of considering other metals, including Fe, in studying Mn neurotoxicity. [Description provided by NIOSH]
• Subjects:
  Biomarkers Manganese Nervous System Occupational Health Respiratory System Safety Welding
• Keywords:
  Author Keywords: Manganese Bioaccumulation Brain Function Inhalation Magnetic Resonance Imaging MRI Neurotoxicity Toenails Welding Fumes
• ISSN:
  0161-813X
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Indiana ; Michigan ; Ohio ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  45-55
• Volume:
  104
• NIOSHTIC Number:
  nn:20069947
• Citation:
  Neurotoxicology 2024 Sep; 104:45-55
• Contact Point Address:
  Ulrike Dydak, School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47906, Unites States
• Email:
  udydak@purdue.edu
• CAS Registry Number:
  Iron (CAS RN 7439-89-6) ; Manganese (CAS RN 7439-96-5)
• Federal Fiscal Year:
  2024
• Performing Organization:
  University of Cincinnati
• Peer Reviewed:
  True
• Start Date:
  20050701
• Source Full Name:
  Neurotoxicology
• End Date:
  20260630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:8cb754da0a62cb1c6afbe92c88458c8bc424ff53d60b4e502d025f47db9e8e543abb3c7112a4f0b1813f42ca2d775388a6f5a25e0d5a21dc69daf0a675d830fd
• Download URL:
  https://stacks.cdc.gov/view/cdc/208265/cdc_208265_DS1.pdf
• File Type:
  [PDF - 3.60 MB ]